1. Field of the Invention
The present invention relates to a disposable filter cartridge comprising a housing, substantially including a bottom and an upright side wall, the underside or bottom having one or more holes, said filter cartridge being provided at its top and at least a part of its bottom with filter material or a filter film, with at least the filter material for the top being connected through a sealed joint to the side wall or a flange-shaped extension thereof, as disclosed in Applicant's Dutch application No. 83.00213 and in British patent No. 1,064,010 to M.I.K.O. and U.S. Pat. No. 3,823,656 to Germaine van der Veken.
These known cartridges serve for making one or more consumption units of coffee: the cartridges may naturally also be used for making other beverages.
In these known filter cartridges, the filter material at the bottom is sealed or thermo-stuck to the circumference of the hole or holes in the bottom.
Also known are disposable filter cartridges whose circumferential side walls of the filter cartridge have upper and lateral extensions respectively in order to form a complete disposable filter with water reservoir. In this case, reference can be made to Belgian patent No. 52.280 to M.I.K.O.
A drawback of these known constructions is that only a limited part of the bottom filter surface, viz. the part of the filter material within the seam, is effectively available for filtration, which results in a relatively low filtration speed and relatively long brewing times. This led to the use of disposable filter cartridges with a relatively large diameter and a thin coffee bed. This, in turn, however, gave a low extraction efficiency.